1. Field of the Invention
The present invention relates to a stator in which one coil wire is wound around each set of a plurality of teeth, and an electric motor equipped with this stator.
2. Description of Related Art
A stator mounted in an electric motor is provided with an iron core in which a plurality of teeth are connected into an integral body. An insulator (an insulating material) is attached to each of the plurality of teeth, and a coil wire is wound around this insulator. In this case, the plurality of teeth are divided into three sets (corresponding to the U-phase, the V-phase, and the W-phase of the electric motor respectively), and one coil wire is wound around each of the three sets of teeth. In this case, it is necessary to route the coil wire between two teeth. So, in a conventional stator, by extending the coil wire wound around the insulator across an outside portion of the insulator (i.e., a portion on a back yoke side), this coil wire is made to reach another insulator (for example, see patent references 1 and 2).    [Patent reference 1] JP,3741600,B    [Patent reference 2] JP,2008-167604,A
A problem with the conventional stator is however that because the coil wire is made to extend across the outside portion of the insulator when routing the coil wire between two teeth, it is necessary to increase the size of the insulator, especially the thickness of the insulator on a side of the back yoke so as to prevent the insulator from yielding to the tensile strength caused by the coil wire. Another problem is that because the coil wire is arranged also in the outside portion of the insulator, it is difficult to ensure the insulation distance between the coil wire arranged in the outside portion of the insulator and the case of the electric motor enclosing the stator and therefore there is a possibility that a short circuit occurs between the coil wire arranged in the outside portion of the insulator and the case of the electric motor. A further problem is that because it is necessary to make the coil wire extend across the outside portion of the insulator, the time required to wind the coil wire around the insulator and the cost of facilities required for the winding increase, and the length of the coil wire wound around the insulator increases.